1. Field of the Invention
The present invention relates to an electronic component such as an electrolytic capacitor. In particular, the present invention relates to a lead unit incorporated in an electrolytic capacitor.
2. Description of the Prior Art
An electrolytic capacitor mounted on a printed wiring board is well known, for example. The electrolytic capacitor includes a capacitor element enclosed in a casing or sheathe. An electrically-conductive tab made of aluminum is attached to the capacitor element, for example. One end of a lead is bonded to the tip end of the electrically-conductive tab. The surface of the lead is coated with a tin plating film prior to the bonding of the lead to the electrically-conductive tab. The tin plating film allows enhancement of the wettability of a solder material. The lead is thus reliably bonded to the printed wiring board when the electrolytic capacitor is mounted on the printed wiring board.
A welding process is employed to bond the lead to the electrically-conductive tab. Stress is generated in the tin plating film at the welded area between the lead and the electrically-conductive tab. So-called whiskers are generated on the tin plating film. When whiskers fall onto the surface of the printed wiring board, a short circuit is caused in wiring patterns on the printed wiring board. It is thus required to reliably prevent the fall of the whiskers.